Vertebral body and disc space replacement devices

ABSTRACT

A vertebral replacement body device for supporting adjacent vertebrae includes a connecting member having an upper member and a lower member engaged thereto at opposite ends thereof. The vertebral replacement body device can have a chamber extending therethrough for fusion of the supported vertebrae.

BACKGROUND

The present invention is directed to devices for replacement of one ormore vertebral bodies and/or one or more disc spaces between vertebraeof a spinal column.

The repair and reconstruction of bony structures is sometimesaccomplished by directly fixing adjacent bony structures to each other,such as by a plate. In other instances, bone growth inducing materialcan be introduced between the adjacent bony structures, which over timeresults in a solid bony connection. In some instances, the adjacent bonystructures are not sufficiently strong to maintain their patency as thebone heals or the bone grows between the adjacent structures through thebone growth inducing material. In these instances, mesh structures orcages have been provided to engage the adjacent bony structures toprovide additional stability. The cages are generally hollow and can beconfigured to contact the harder cortical bone of the adjacent bonystructures. The hollow portion of the cages can be filled with bonegrowth inducing material.

Devices have also been provided to replace a removed vertebral body andto provide a support structure between the remaining vertebrae on eitherside of the one or more removed vertebral bodies. One example of such adevice is provided in U.S. Pat. No. 5,192,327.

The '327 patent describes oval or hemi-oval rings which can be used inisolation in a disc space or stacked one upon another in interdigitatingfashion for replacement of a vertebral body. The rings have ridges alongtheir top and bottom faces that form peaks and valleys to allow thestacked rings to interdigitate when stacked. One problem with theseinterdigitating ridges is that the stack of rings can slide relative toone another in the direction of the ridges when stacked. The '327 patentalso discloses a connecting bar extending through the stacked ringstransversely to the ridges to prevent relative sliding between thestacked rings. In order to use the connecting bar in surgery, thesurgeon must be provided with a multitude of bars of differing heightsand/or “custom fit” the bar as needed for the height of the particularset of stacked cages. In addition, the stacked cages can separatelongitudinally even when the connecting bar extends through the stackedcages.

While prior devices are a step in the right direction, there remains aneed for improved devices for replacing one or more vertebral bodiesand/or one or more disc spaces in a spinal column. The present inventionis directed to satisfying these needs, among others.

DESCRIPTION OF THE FIGURES

FIG. 1 is a perspective view of a vertebral replacement body deviceaccording to one embodiment of the present invention.

FIG. 2 is an exploded perspective view of the vertebral replacement bodydevice of FIG. 1.

FIG. 3 is a side elevation view of the vertebral replacement body deviceof FIG. 1 in partial section to illustrate the interconnection betweenend members and a connecting member of the device.

FIG. 4 is an elevational view of an engaging member comprising a portionof the connecting member of the device of FIG. 1.

FIG. 5 is an end view of the vertebral replacement body device of FIG.1.

FIG. 6 is a perspective view of an end member comprising a portion ofthe vertebral replacement body device of FIG. 1.

FIG. 7 is an elevation view of the end member of FIG. 6.

FIG. 8 is an elevational view of the vertebral replacement body deviceof FIG. 1 positioned in the spinal column between two vertebrae.

FIG. 9 is an elevational view of one of the end members comprising aportion of the vertebral replacement body device of FIG. 1 positioned ina spinal disc space between adjacent vertebrae.

FIG. 10 is a perspective view of another embodiment vertebralreplacement body device.

FIG. 11 is an exploded perspective view of another embodiment vertebralreplacement body device.

DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

For the purpose of promoting an understanding of the principles of theinvention, reference will now be made to the illustrated embodimentsthereof and specific language will be used to describe the same. It willnevertheless be understood that no limitation of the scope of theinvention is thereby intended. Any such alterations and furthermodifications in the invention, and any such further applications of theprinciples of the invention as described herein are contemplated aswould normally occur to one skilled in the art to which the inventionrelates.

The present invention relates to devices for replacing one or morevertebral bodies in the spinal column and/or one or more disc spacesbetween adjacent vertebrae. It is contemplated that the vertebralreplacement body device will support adjacent ones of the intactvertebrae during fusion thereof. It is further contemplated that one ormore components of the vertebral replacement body device can bepositioned in a disc space between adjacent vertebrae for supporting theadjacent vertebrae during fusion thereof.

The device can employ current mesh or cage-type devices for engagementwith adjacent bony structures, although other types of bone supportingdevices are also contemplated. The vertebral replacement body device canhave a tubular form with a hollow chamber extending therethrough. Theadjacent vertebrae are supported by opposite ends of the device and thechamber can be filled with bone growth inducing or osteogeneticmaterial. The ends of the device include flattened plateau-like endsurfaces that can be formed at the junction between bars defining themesh wall structure of the device.

The vertebral replacement body device includes a middle or connectingmember and at least one of an upper member attached to an upper end ofthe connecting member and/or a lower member attached to a lower end ofthe connecting member. Each of the upper member, the lower member andthe connecting member can have a generally kidney bean cross-sectionalshape in the plane transverse to the central axis of the assembleddevice. Other cross-sectional shapes are also contemplated, includingcircular, racetrack-shaped, rectangular, square, oval, D-shaped,triangular, or other polygonal shape. Each of the upper member and thelower member can include an interior chamber. The connecting member canalso include an interior chamber that generally aligns with the interiorchambers of the upper and lower members engaged thereto.

The upper and lower members can be fabricated from a tubular mesh havingapertures through its wall. One example of a tubular mesh is provided inU.S. Pat. No. 5,897,556, which is incorporated herein by reference inits entirety. The connecting member can also be fabricated from atubular mesh. Further forms contemplate that the upper and lower membersand the connecting member can be a tubular body with solid walls.

The upper and lower members can be telescopically and non-rotatablyengaged with the connecting member. In one embodiment, the connectingmember includes an upper extension and a lower extension extendingtherefrom. The upper and lower extensions are in the form ofsubstantially continuous rings extending around the respective ends ofthe connecting member. Other forms for the upper and lower extensionsare also contemplated. The upper and lower extensions are received inthe interior chamber of the respective upper or lower member when theupper and lower members are engaged to the connecting member. In anotherembodiment, extensions are provided on the upper and lower members, andthese extensions are received in an interior chamber or opening atrespective ends of the connecting member.

Each of the upper and lower extensions, and each of the chambers of theupper and lower members, can have a non-circular cross-section andinterface to prevent relative rotation between the connecting member andthe upper or lower member engaged thereto.

The upper and lower extensions of the connecting member each include anengaging member which can be flexed inwardly as the respective upper orlower member is placed around the respective extension of the connectingmember. The engaging member fits into an opening or aperture in theinner wall surface of the respective upper and lower member to axiallysecure the respective upper and lower members to the connecting member.

The vertebral replacement body device can be made from any biocompatiblematerial, including synthetic or natural autograft, allograft orxenograft tissues, and can be resorbable or non-resorbable in nature.Examples of tissue materials include hard tissues, connective tissues,demineralized bone matrix and combinations thereof. Further examples ofresorbable materials are polylactide, polyglycolide, tyrosine-derivedpolycarbonate, polyanhydride, polyorthoester, polyphosphazene, calciumphosphate, hydroxyapatite, bioactive glass, and combinations thereof.Further examples of non-resorbable materials are non-reinforcedpolymers, carbon-reinforced polymer composites, PEEK and PEEKcomposites, shape-memory alloys, titanium, titanium alloys, cobaltchrome alloys, stainless steel, ceramics and combinations thereof andothers as well.

Any suitable osteogenetic material or composition is contemplated forplacement within the chambers defined by the upper member, the lowermember and the connecting member. Such osteogenic material includes, forexample, autograft, allograft, xenograft, demineralized bone, syntheticand natural bone graft substitutes, such as bioceramics and polymers,and osteoinductive factors. Where bony material is placed within thechambers of the components of the vertebral replacement body device, thematerial can be pre-packed into the hollow chambers before the device isimplanted, or can be pushed through the plurality of wall openings afterthe device is in position in the spinal column. A separate carrier tohold the materials within the chambers of the device can also be used.These carriers can include collagen-based carriers, bioceramicmaterials, such as BIOGLASS®, hydroxyapatite and calcium phosphatecompositions. The carrier material can be provided in the form of asponge, a block, folded sheet, putty, paste, graft material or othersuitable form. Moreover, the osteogenetic compositions contained withinthe vertebral replacement body device can comprise an effective amountof a bone morphogenetic protein, transforming growth factor β1,insulin-like growth factor 1, platelet-derived growth factor, fibroblastgrowth factor, LIM mineralization protein (LMP), and combinationsthereof or other therapeutic or infection resistant agent, held within asuitable carrier material.

In FIGS. 1-2, a vertebral replacement body device 10 includes a middleor connecting member 12, an upper member 30, and a lower member 40.Device 10 is illustrated as having a tubular form that extends along alongitudinal axis L and defines a chamber extending therethrough alongaxis L. Bone growth can occur through this chamber for fusion betweenthe vertebral bodies supported at each end of device 10.

Connecting member 12 includes a body 14 extending between an upper end14 a and an opposite lower end 14 b. Connecting member 12 furtherincludes an upper extension 18 a and a lower extension 18 b. Connectingmember 12 has an inner wall surface 12 a (FIG. 5) that defines a chamber16 extending between and opening at the outer ends of the extensions 18a, 18 b. Each of the extensions 18 a, 18 b extends outwardly from therespective end 14 a, 14 b of body 14 and around chamber 16. End surface15 a extends around upper extension 18 a, and end surface 15 b extendsaround lower extension 18 b. In the illustrated embodiment, extensions18 a, 18 b are substantially continuous rings extending from theirrespective end 14 a, 14 b. Other embodiments contemplate other forms forthe extensions, such as, for example, a series of two or more flexibleengaging members (such as engaging member 20 discussed below) or rigidengaging members.

The wall of body 14 includes a number of triangular apertures 22 whichextend through the wall and communicate with chamber 16. Other shapesfor apertures 22 are also contemplated, including non-circular shapessuch as a square, diamond, oval and/or rectangular shapes, circularshapes, and/or polygonal shapes. The wall of body 14 also includes anumber of holes 24 extending at least partially therethrough. Holes 24can be threaded or otherwise sized and/or configured for engagement withone or more insertion instruments (not shown.)

Referring further to FIGS. 3-5, the substantially continuous wall ofeach of the extensions 18 a, 18 b is interrupted by an engaging member20. Only engaging member 20 for upper extension 18 a is illustrated, itbeing understood that lower extension 18 b can also be provided with anidentical or similar engaging member. Engaging members 20 secure uppermember 30 and lower member 40 to respective ends of connecting member12, resisting axial dislocation of upper member 30 and lower member 40away from connecting member 12 along axis L. Engaging members 20 canalso resist axial rotation of upper and lower members 30, 40 relative toconnecting member 12 about axis L. Other embodiments contemplate thatmore than one engaging member 20 is provided in the wall of one or bothof the extensions 18 a, 18 b. Further embodiments contemplate that wallof one or both of the extensions 18 a, 18 b is not substantiallycontinuous, but rather is continuous or includes a number of discretewall portions sufficiently spaced and sized about body 14 of connectingmember 12 for engagement with upper and lower members 30, 40.

Engaging member 20 includes a projection or engaging portion 20 b and astem 20 a connected or integrally formed with end surface 15 a of body14. Stem 20 a has a reduced thickness to allow engaging member 20 todeflect inwardly in response to a force applied to engaging portion 20b. Engaging portion 20 b projects outwardly from stem 20 a and has atriangular shape tapering from an engaging surface 20 c to an upper end20 d. Other configurations for engaging member 20 are also contemplated.For example, engaging member 20 can be provided with an engaging portion20 b in the form of a partially spherical or rounded nub, a receptacle,rectangular or polygonal shaped tab or projection. Engaging portion 20 bcan also correspond to the shape the aperture 22 in which it isreceived. Engaging member 20 can also be a snap ring, collet, bayonetlock, or surface irregularity that resists axial movement of the engagedupper member 30 and lower member 40 away from connecting member 12 alongaxis L.

Referring also to FIGS. 6-7, upper and lower members 30, 40 areillustrated as being identical, although it is also contemplated thatupper member 30 and lower member 40 can be provided with differentconfigurations and/or sizes. With respect to FIGS. 6 and 7, only uppermember 30 will be further described, it being understood that lowermember 40 can be provided with identical features.

Upper member 30 includes a body 32 extending between an upper end 32 aand a lower end 32 b. Body 32 has a height H2 between the upper andlower ends 32 a, 32 b. Height H2 can be selected so that upper member 30fits within an intervertebral disc space between adjacent vertebrae.Upper end 32 a and lower end 32 b can be sloped to converge toward oneanother and form a height H2′ opposite height H2. The sloped ends 32 a,32 b allow upper member 30 to restore and/or conform to the naturalinclination between the adjacent endplates of the vertebral bodies. Itis further contemplated that ends 32 a, 32 b can be parallel to oneanother.

Body 32 has an inner wall surface 32 c defining a chamber 34 thatextends between and opens at ends 32 a, 32 b. As shown in FIG. 5, body32 has an outer surface 32 d that defines a kidney-shaped cross sectiontransverse to longitudinal axis L. Other cross-sectional shapes are alsocontemplated, including, for example, circular cross-sections andnon-circular cross-sections, such as oval, triangular, square,rectangular, polygonal, boomerang shaped, D-shaped, or racetrack shapedcross-sections. In the illustrated embodiment, connecting member 12 hasthe same cross-sectional shape as the upper and lower members 30, 40 toprovide a vertebral replacement body device of uniform cross-sectionalshape and size along its height.

Body 32 defines a number of triangular apertures 36 extending at leastpartially therethrough in communication with chamber 34, and a number ofcircular holes 38 extending at least partially therethrough from theexterior surface of body 32. Holes 38 or the other holes can be threadedor otherwise sized and/or configured for engagement with one or moreinsertion instruments.

Body 32 further includes a number of bearing surfaces 32 e spaced aroundfirst end 32 a and bearing surfaces 32 f spaced around second end 32 b.Adjacent ones of each of the bearing surfaces 32 e are separated fromone another by V-shaped recesses 32 g. Adjacent ones of each of thebearing surfaces 32 f are separated from one another by V-shapedrecesses 32 h. Bearing surfaces 32 e, 32 f are planar and provide anumber of plateau-like, generally flat bearing surfaces spaced about therespective end of body 32. Bearing surfaces 32 e, 32 f have atrapezoidal shape in the illustrated embodiment, although other shapesare also contemplated. In the illustrated embodiment, ten such bearingsurfaces 32 e, 32 f are provided at each end of body 32. It is alsocontemplated that fewer than ten or more than ten bearing surfaces couldbe provided. It is further contemplated that each end of body 32 couldbe provided with a single, continuous bearing surface extending aroundchamber 34.

The plateau-like bearing surfaces 32 e, 32 f provide a surface areaabout the ends of body 32 for bearing support of the adjacent vertebralendplate and to resist subsidence of body 32 into the vertebrae. Theplateau-like bearing surfaces 32 e, 32 f provide surface area contactbetween the end of body 32 and the adjacent endplate, providingfrictional resistance to body 32 sliding or twisting relative to theadjacent vertebral endplate.

Upper member 30 and lower member 40 are connected to respective ends ofconnecting member 12 to provide vertebral replacement body device 10.Upper member 30 is advanced over upper extension 18 a so that upperextension 18 a extends into chamber 34. Engaging member 20 flexesinwardly as inner wall surface 32 c of body 32 passes along engagingportion 20 b. Engaging portion 20 b is configured to reside within oneof the apertures 36 extending into the wall of body 32 from chamber 34.When engaging portion 20 b and the respective aperture 36 are aligned,engaging member 20 returns towards its pre-insertion position withengaging portion 20 b residing in the respective aperture 36. Thisengages upper member 30 to connecting member 12, resisting movement ofupper member 30 away from connecting member 12 along axis L. It isfurther contemplated engaging surface 20 c engages the adjacent lowersurface of the respective aperture 36 to provide a positive seat betweenbearing surface 15 a of connecting member 12 and bearing surfaces 32 fabout end 32 b of upper member 30. Lower member 40 is secured to lowerextension 18 b in a similar manner.

Bearing surfaces 32 f at lower end 32 b of upper member 30 bear againstend surface 15 a extending about upper extension 18 a of connectingmember 12. This bearing relationship transmits the spinal column loadfrom upper member 30 to connecting member 12. The bearing surfaces ofthe lower member 40 similarly bear against end surface 15 b extendingabout lower extension 18 b of connecting member 12. The end surfaces 15a, 15 b at the ends of body 14 and the adjacent bearing surfaces of theupper and lower members 30, 40 do not interdigitate. This bearingrelationship eliminates stress concentrations and shifting of thecomponents of device 10 that might result from improperly alignedinterdigitating surfaces.

Axial rotation of upper member 30 and lower member 40 relative toconnecting member 12 is resisted by the interface between upper andlower extensions 18 a, 18 b and the respective inner wall surface of theupper and lower members 30, 40. In the illustrated embodiment,extensions 18 a, 18 b have a non-circular shape, such as the kidneyshape shown in FIG. 5. Similarly, the inner wall surface 32 c of uppermember 30 and also the inner wall surface of lower member 40 have anon-circular shape sized to receive in form fitting engagement therespective upper or lower extension 18 a, 18 b. This non-circular formfitting engagement prevents rotation of upper member 30 and lower member40 relative to connecting member 12.

Device 10 can be used to replace a vertebra that has been removed fromthe spinal column segment using known techniques. Device 10 is assembledby securing upper member 30 to one end of connecting member 12 andsecuring lower member 40 to the other end of connecting member 12. Thisprovides a vertebral replacement body device 10 that has an overallheight that is equal to the sum of the heights H1 of body 14, height H2of upper member 30, and height H3 of lower member 40 (FIG. 3.)

As shown in FIG. 8, the assembly 10 can be placed between vertebra V1and vertebra V3 after removal of vertebra V2. Replacement of more thanone vertebra is also contemplated. Although not required, it iscontemplated that height H1 could be representative of that of theremoved vertebra and heights H2, H3 could be representative of theheights of the respective disc spaces between the removed vertebra V2and the remaining vertebrae V1, V3. Also shown in FIG. 8 is astabilization construct 150 engaged to and extending between vertebraeV1 and V3 to support and stabilize the spinal column segment before,during and, if construct 150 is non-resorbable and left in the patient,after fusion. Stabilization construct 150 can be a rod system, platesystem or artificial ligament system. It is further contemplated thatstabilization system could be attached to any portion of vertebrae V1and V3, including the anterior, antero-lateral, lateral, postero-lateralor posterior portions.

It is also contemplated that heights H2 and H3 could be identical ordifferent, and that the ends of upper and lower members 30, 40 could beprovided with the same or differing angles of inclination. It is furthercontemplated that device 10 can comprise a kit having a number of uppermembers 30 and lower members 40 of various sizes and heights H2, H3. Akit could also include a number of connecting members 12 of varioussizes and heights H1. Such a kit would provide the surgeon flexibilityin selecting the appropriately size and height for members of a device10 based on conditions encountered in surgery.

FIG. 9 illustrates placement of one of the upper or lower members 30, 40in disc space S between adjacent vertebrae V1, V2 to function as aninterbody fusion device. Engagement of stabilization construct tovertebrae V1 and V2 is also contemplated.

It is also contemplated that connecting member 12 could be provided withone end configured to bear against a vertebral endplate, and that onlyone of the upper and lower members 30, 40 is engaged to the other end ofconnecting member 12. The assembled device could then be placed betweenadjacent vertebrae with an end of connecting member 12 and an end of theselected upper or lower member 30, 40 in contact with the adjacentvertebral endplates.

In FIG. 10 there is provided an alternate embodiment vertebralreplacement body device 100. Device 100 includes upper member 30 andlower member 40 engaged at opposite ends of a connecting member 12′,which can be similar to connecting member 12 discussed above. Connectingmember 12′ does not include upper and lower extensions extending fromend 14 a′ and 14 b′. To secure upper member 30 and lower member 40 toconnecting member 12′, a sleeve 112 is provided around connecting member12′ that has an upper end 114 a overlapping upper member 30 and a lowerend 114 b overlapping lower member 40.

Sleeve 112 can be provided with engaging members 117 a, 117 b in theform of projections, engaging members, tabs or the like on its innerwall surface. Engaging members 117 a, 117 b engage apertures 36, 46 orother receptacle or detent in the outer wall surfaces of upper member 30and lower member 40, respectively. Engaging members could also beprovided to engage apertures 22′ or other receptacle or detent inconnecting member 12′. So engaged, sleeve 112 resists axial movement ofupper member 30 and lower member 40 relative to connecting member 12′.

It is further contemplated that rotation of upper member 30 and lowermember 40 relative to connecting member 12′ could be prevented by anon-circular, telescoping interface between the members such asdiscussed above. In another embodiment, rotation of upper member 30 andlower member 40 relative to connecting member 12′ could be prevented bythe engagement of sleeve 112 with the upper and lower members 30, 40and, if so configured, with connecting member 12′. In yet a further formof the embodiment of FIG. 10, the connecting member 12′ could beintegral with sleeve member 112 to provide upper and lower bearingsurfaces within sleeve 112 for support of upper member 30 and lowermember 40 thereon.

Referring now to FIG. 11, another embodiment vertebral replacement bodydevice 210 is shown. Device 210 includes a connecting member 212 havinga body 214 extending between an upper end 214 a and a lower end 214 b.Upper end 214 a includes an upper extension 218 a having an end surface215 a therearound. Extension 218 a extends around a bearing surface 216at the upper end of chamber 220. Bearing surface 216 is positioned belowend surface 215 a in chamber 220. Second end 215 b similarly includes anextension 218 b having an end surface 215 b, and a bearing surface (notshown) at the lower end of chamber 220 below end surface 215 b.

Upper member 230 includes a body 232 having an upper end 232 a and alower end 232 b. Body 232 extends around a chamber 234. Lower member 240includes a body 242 having a lower end 242 a and an upper end 242 b.Body 242 extends around a chamber 244. Lower member 240 includes aninset wall 248 extending around chamber 244, and a bearing surface 250extending around body 242 below inset wall 248. Upper member 230similarly includes an inset wall 238 and a bearing surface (not shown)extending around body 232 above inset wall 238.

When assembled, inset wall 238 of upper member 230 is received inchamber 220 of connecting member 212 with extension 218 a extendingaround inset wall 238. Similarly, inset wall 248 of lower member 240 isreceived in chamber 220 of connecting member 212 with extension 218 bextending around inset wall 248. It contemplated that end surface 215 acan contact the bearing surface extending around inset wall 238, andthat end surface 215 b can contact bearing surface 250 extending aroundinset wall 248. Additionally or alternatively, the lower end of insetwall 238 can contact bearing surface 216 in chamber 220 at the upper endof connecting member 212, and the upper end of inset wall 248 cancontact the bearing surface (not shown) in chamber 220 at the lower endof connecting member 212.

Connecting member 212 and/or upper and lower members 230, 240 could beprovided with engaging members or a sleeve such as discussed above toprevent axial and/or rotational movement of upper and lower members 230,240 relative to connecting member 212 when device 210 is assembled. In afurther embodiment, connecting member 212 does not include the upperbearing surface 216 and the lower bearing surface in chamber 220 sinceextensions 218 a, 218 b are not provided on connecting member 212. Inthis embodiment, inset walls 238 and 248 are received in chamber 220 atthe respective end of connecting member 212, and end surfaces 215, 215 bcontact respective ones of the bearing surfaces extending around insetwalls 238, 248.

While the invention has been illustrated and described in detail in thedrawings and foregoing description, the same is to be considered asillustrative and not restrictive in character, it being understood thatonly the preferred embodiments have been shown and described and thatall changes and modifications that come within the spirit of theinvention are desired to be protected.

What is claimed is:
 1. A vertebral replacement body device, comprising:an upper member having a first end for engaging an endplate of an uppervertebral body and an opposite second end, said upper member having awall defining a chamber extending between said first end and said secondend; a lower member having a first end for engaging an endplate of alower vertebral body and an opposite second end, said lower memberhaving a wall defining a chamber extending between said first end andsaid second end; and a connecting member positionable between said uppermember and said lower member, said connecting member having a chamberextending therethrough and including a body having an upper end and alower end, said connecting member further including an upper extensionat said upper end of said body and a lower extension at said lower endof said body, said upper extension including a flexible upper engagingmember having a projection engageable with said wall of said uppermember and said lower extension including a flexible lower engagingmember having a projection engageable with said wall of said lowermember.
 2. The device of claim 1, wherein: said upper extension ispositionable in said chamber of said upper member such that said uppermember is non-rotatably engaged with said connecting member; and saidlower extension is positionable in said chamber of said lower membersuch that said lower member is non-rotatably engaged with saidconnecting member.
 3. The device of claim 1, wherein said upperextension and said lower extension are each a substantially continuousring member interrupted by said respective engaging member.
 4. Thedevice of claim 1, wherein each of said upper and lower engaging membersflexes inwardly toward said chamber of said connecting member asrespective ones of said upper member and said lower member are engagedto said connecting member.
 5. The device of claim 1, wherein said upperengaging member is integrally formed with said upper end of said body ofsaid connecting member and said lower engaging member is integrallyformed with said lower end of said body of said connecting member. 6.The device of claim 1, wherein said upper end of said body of saidconnecting member defines an upper end surface extending about saidupper extension and said lower end of said body of said connectingmember defines a lower end surface extending about said lower extension,said upper extension projecting beyond said upper end surface and saidlower extension projecting beyond said lower end surface.
 7. The deviceof claim wherein: said second end of said upper member includes a seriesof flattened end surfaces spaced therearound for bearing against saidupper end surface of said connecting member; and said second end of saidlower member includes a series of flattened end surfaces spacedtherearound for bearing against said lower end surface of saidconnecting member.
 8. The device of claim 1, wherein: said upper memberincludes at least one aperture extending through said wall of said uppermember; and said lower member includes at least one aperture extendingthrough said wall of said lower member.
 9. The device of claim 8,wherein each of said upper and lower engaging members includes anengaging portion positionable in said at least one aperture ofrespective ones of said upper member and said lower member.
 10. Thedevice of claim 9, wherein each of said upper and lower engaging membersincludes an engaging surface that engages a surface of said at least oneaperture to resist axial displacement of respective ones of said uppermember and said lower member relative to said connecting member.
 11. Thedevice of claim 10, wherein each said at least one apertures of saidupper member and said lower member has a triangular shape and each ofsaid engaging portions has a triangular shape sized to fit within saidat least one aperture.
 12. A vertebral replacement body device,comprising: an upper member having a first end for engaging an endplateof an upper vertebral body and an opposite second end, said upper memberdefining a chamber extending between said first end and said second end;a lower member having a first end for engaging an endplate of a lowervertebral body and an opposite second end, said lower member defining achamber extending between said first end and said second end; aconnecting member between said upper member and said lower member, saidconnecting member including a chamber extending therethrough andincluding a body having an upper end and a lower end, said connectingmember further including an upper extension at said upper end of saidbody and a lower extension at said lower end of said body, said upperextension being positionable in said chamber of said upper member suchthat said upper member is non-rotatably engaged with said connectingmember and said lower extension being positionable in said chamber ofsaid lower member such that said lower member is non-rotatably engagedwith said connecting member, wherein: said upper extension includes aflexible engaging member having a projection engageable with an openingin a wall of said upper member; and said lower extension includes aflexible engaging member having a projection engageable with an openingin a wall of said lower member.
 13. The device of claim 12, wherein:said chamber of said upper member and said chamber of said connectingmember align with one another when said upper member is engaged to saidconnecting member; and said chamber of said lower member and saidchamber of said connecting member align with one another when said lowermember is engaged to said connecting member.
 14. The device of claim 12,wherein: the vertebral replacement body device has a longitudinal axisextending therethrough; and said upper member, said lower member andsaid connecting member each have a kidney shaped cross-sectiontransverse to said longitudinal axis.
 15. The device of claim 12,wherein said upper member, said connecting member and said lower memberare comprised of resorbable material selected from the group consistingof: hard tissues, connective tissues, demineralized bone matrix,polylactide, polyglycolide, tyrosine-derived polycarbonate,polyanhydride, polyorthoester, polyphosphazene, calcium phosphate,hydroxyapatite, bioactive glass, and combinations thereof.
 16. Thedevice of claim 12, further comprising a stabilization constructextending between and engaged to the upper vertebral body and the lowervertebral body.
 17. The device of claim 12, wherein: said vertebralreplacement body has a longitudinal axis extending therethrough; saidupper extension has a non-circular shape transverse to said longitudinalaxis; and said lower extension has a non-circular shape transverse tosaid longitudinal axis.
 18. The device of claim 17, wherein: saidchamber of said upper member has a non-circular cross-sectional shapetransverse to said longitudinal axis and said upper extension isreceived in said chamber in form fitting engagement with an inner wallsurface of said upper member; and said chamber of said lower member hasa non-circular cross-sectional shape transverse to said longitudinalaxis and said lower extension is received in said chamber in formfitting engagement with an inner wall surface of said lower member. 19.The device of claim 12, wherein said upper end of said body of saidconnecting member defines an upper end surface extending radially aboutsaid upper extension and said lower end of said body of said connectingmember defines a planar surface extending radially about said lowerextension, said upper extension projecting beyond said upper end surfaceand said lower extension projecting beyond said lower end surface. 20.The device of claim 19, wherein: said second end of said upper memberincludes a series of flattened end surfaces spaced therearound forbearing against said upper end surface of said connecting member; andsaid second end of said lower member includes a series of flattened endsurfaces spaced therearound for bearing against said lower end surfaceof said connecting member.
 21. The device of claim 12, wherein saidupper member, said connecting member and said lower member are comprisedof non-resorbable material selected from the group consisting of:non-reinforced polymers, carbon-reinforced polymer composites, PEEK,PEEK composites, shape-memory alloys, titanium, titanium alloys, cobaltchrome alloys, stainless steel, ceramics and combinations thereof. 22.The device of claim 21, wherein said upper member, said connectingmember and said lower member are each comprised of PEEK material. 23.The device of 12, further comprising bone growth material in saidchamber of each of said upper member, said connecting member and saidlower member.
 24. The device of claim 23, said bone growth materialincludes one or more selected from group consisting of: bonemorphogenetic protein, transforming growth factor β1, insulin-likegrowth factor 1, platelet-derived growth factor, fibroblast growthfactor, and LIM mineralization protein (LMP).
 25. The device of claimsaid bone growth material is provided in a carrier having a formselected from the group consisting of: a sponge, a block, folded sheet,putty, and paste.
 26. The device of claim 12, wherein said upper memberhas a wall extending about said chamber, said wall defining a pluralityof openings therethrough communicating with said chamber; and said lowermember has a wall extending about said chamber, said wall defining aplurality of openings therethrough communicating with said chamber. 27.The device of wherein said connecting member includes a chamberextending therethrough and said body of said connecting member includesa wall extending around said chamber, said wall including a plurality ofopenings therethrough in communication with said chamber of saidconnecting member.
 28. The device of claim 26, wherein at least one ofsaid plurality of openings of each of said upper member and said lowermember has a triangular shape.
 29. The device of claim 12, wherein: saidfirst end of said upper member includes a series of flattened endsurfaces spaced therearound for bearing against the endplate of theupper vertebral body; and said first end of said lower member includes aseries of flattened end surfaces spaced therearound for bearing againstthe endplate of the lower vertebral body.
 30. The device of claim 29,wherein said flattened end surfaces of each of said upper member andsaid lower member have a trapezoidal shape.
 31. The device of claim 29,wherein said flattened end surfaces of each of said upper member andlower member extend generally parallel to an adjacent vertebralendplate.
 32. A vertebral replacement body device, comprising: an uppermember having a first end for engaging an endplate of an upper vertebralbody and an opposite second end, said upper member having a walldefining a chamber extending between said first end and said second end;a lower member having a first end for engaging an endplate of a lowervertebral body and an opposite second end, said lower member having awall defining a chamber extending between said first end and said secondend; a connecting member positionable between said upper member and saidlower member, said connecting member having a body with an upper end anda lower end, said connecting member further including an upper extensionat said upper end of said body and a lower extension at said lower endof said body, wherein said upper extension includes a flexible upperengaging member having a projection engageable with said wall of saidupper member and said lower extension includes a flexible lower engagingmember having a projection engageable with said wall of said lowermember, wherein: said upper end of said body of said connecting memberincludes an upper end surface adjacent to said upper extension; saidlower end of said body of said connecting member includes an end surfaceadjacent to said lower extension; said second end of said upper memberincludes an end surface bearing against said upper end surface of saidconnecting member; and said second end of said lower member includes anend surface bearing against said lower end surface of said connectingmember.
 33. The device of claim therein said second end of said uppermember includes a series of flattened end surfaces spaced therearound;and said second end of said lower member includes a series of flattenedend surfaces spaced therearound.
 34. The device of claim 32, whereinsaid upper engaging member is integrally formed with said upper end ofsaid body of said connecting member and said lower engaging member isintegrally formed with said lower end of said body of said connectingmember.
 35. The device of claim 32, wherein each of said upper and lowerengaging members includes an engaging portion forming said projection.36. The device of claim 32, wherein each of said upper and lowerengaging members includes an engaging surface that engages a surface ofat least one aperture in said wall of each of said upper member and saidlower member to resist axial displacement of said upper member and saidlower member relative to said connecting member.
 37. The device of claim32, said upper member is telescopically and non-rotabably positionableabout said upper extension and said lower member is telescopically andnon-rotatably positionable about said lower extension.
 38. The device ofclaim 32, wherein said upper member is telescopically and non-rotabablypositionable within said upper extension and said lower member istelescopically and non-rotatably positionable within said lowerextension.
 39. The device of claim 32, further comprising a sleeve aboutsaid connecting member and at least a portion of said upper member andsaid lower member, said sleeve engaging at least said upper member andsaid lower member to maintain said end surfaces of said upper and lowermembers in contact with a respective one of said upper and lower endsurfaces of said connecting member.
 40. A vertebral replacement bodydevice, comprising: an upper member having a first end for engaging anendplate of an upper vertebral body and an opposite second end, saidupper member having a wall defining a chamber extending between saidfirst end and said second end; a lower member having a first end forengaging an endplate of a lower vertebral body and an opposite secondend, said lower member having a wall defining a chamber extendingbetween said first end and said second end; a connecting memberpositionable between said upper member and said lower member, saidconnecting member having a body with an upper end and a lower end, saidconnecting member further including an upper extension at said upper endof said body and a lower extension at said lower end of said body,wherein: said upper end of said body of said connecting member includesan upper end surface adjacent to said upper extension; said lower end ofsaid body of said connecting member includes an end surface adjacent tosaid lower extension; said second end of said upper member includes anend surface bearing against said upper end surface of said connectingmember; said second end of said lower member includes an end surfacebearing against said lower end surface of said connecting member; and asleeve about said connecting member and at least a portion of said uppermember and said lower member, said sleeve engaging at least said uppermember and said lower member to maintain said end surfaces of said upperand lower members in contact with a respective one of said upper andlower end surfaces of said connecting member.
 41. The device of claim40, wherein said second end of said upper member includes a series offlattened end surfaces spaced therearound; and said second end of saidlower member includes a series of flattened end surfaces spacedtherearound.
 42. The device of claim 40, wherein said upper member istelescopically and non-rotabably positionable about said upper extensionand said lower member is telescopically and non-rotatably positionableabout said lower extension.
 43. The device of claim 40, said uppermember is telescopically and non-rotabably positionable within saidupper extension and said lower member is telescopically andnon-rotatably positionable within said lower extension.
 44. The deviceof claim 40, said upper extension includes a flexible upper engagingmember having a projection engageable with said wall of said uppermember and said lower extension includes a flexible lower engagingmember having a projection engageable with said wall of said lowermember.
 45. The device of claim 44, wherein each of said upper and lowerengaging members includes an engaging portion forming said projection.46. The device of claim 44, wherein said upper engaging member isintegrally formed with said upper end of said body of said connectingmember and said lower engaging member is integrally formed with saidlower end of said body of said connecting member.
 47. The device ofclaim 44, wherein each of said upper and lower engaging members includesan engaging surface that engages a surface of at least one aperture insaid wall of each of said upper member and said lower member to resistaxial displacement of said upper member and said lower member relativeto said connecting member.
 48. A vertebral replacement body device,comprising: an upper member having a first end for engaging an endplateof an upper vertebral body and an opposite second end, said upper memberhaving a wall defining a chamber extending between said first end andsaid second end; a lower member having a first end for engaging anendplate of a lower vertebral body and an opposite second end, saidlower member having a wall defining a chamber extending between saidfirst end and said second end; a connecting member positionable betweensaid upper member and said lower member, said connecting memberincluding a body having a chamber extending between an upper end and alower end of said body, wherein: said connecting member and said uppermember are telescopically and non-rotatably positionable with respect toone another for placement of said second end of said upper memberagainst said upper end of said connecting member; said connecting memberand said lower member are telescopically and non-rotatably positionablewith respect to one another for placement of said second end of saidlower member against said upper end of said connecting member; and saidconnecting member further includes an upper extension at said upper endof said body and a lower extension at said lower end of said body, saidupper extension including a flexible upper engaging member having aprojection engageable with said wall of said upper member and said lowerextension including a flexible lower engaging member having a projectionengageable with said wall of said lower member.
 49. The device of claim48, wherein said upper extension and said lower extension are each asubstantially continuous ring member interrupted by said respectiveengaging member.
 50. The device of claim 48, wherein said upper memberincludes a lower extension at said second end of said lower memberpositionable in said chamber of said connecting member and said lowermember includes an upper extension at said second end of said lowermember positionable in said chamber of said connecting member.
 51. Amethod for assembling a vertebral replacement body device, comprising:providing a connecting member having a body extending between an upperend and a lower end; telescopically and non-rotatably engaging an uppermember to the upper end of the connecting member with an end of theupper member in contact with the upper end of the body; andtelescopically and non-rotatably engaging a lower member to the lowerend of the connecting member with an end of the lower member in contactwith the lower end of the body, wherein telescopically and non-rotatablyengaging the upper member to the connecting member and telescopicallyand non-rotatably engaging the lower member to the connecting memberincludes placing a sleeve about the upper member, the connecting memberand the lower member.
 52. The method of claim 51, further comprising:engaging an aperture of the upper member with an engagement memberextending from the upper end of the body of the connecting member; andengaging an aperture of the lower member with an engagement memberextending from the lower end of the body of the connecting member. 53.The method of claim 51, further comprising: placing bone growth materialin a chamber of said connecting member, a chamber of said upper member,and a chamber of said lower member.
 54. The method of claim 51, whereinthe vertebral replacement body defines a longitudinal axis andnon-rotatably engaging the upper member and the lower member includesproviding an interference fit between the connecting member andrespective ones of the upper member and lower member about thelongitudinal axis.
 55. The method of claim 51, wherein telescopicallyengaging the upper member and the lower member includes positioning aportion of the connecting member in a chamber of each the upper memberand the lower member.
 56. The method of claim 51, wherein telescopicallyengaging the upper member and the lower member includes: positioning aportion of the upper member in a chamber of the connecting member; andpositioning a portion of the lower member in a chamber of the connectingmember.